The present invention relates to waterjet cutting systems and methods of operating same. More particularly, the present invention relates to an apparatus that controls the delivery of abrasive particulate material from a storage chamber to the outlet of a waterjet cutting machine. Further, the present invention relates to a method of controlling the flow of abrasive particulate material to a nozzle of such waterjet cutting machine.
Abrasive waterjet cutting systems, where useful work is done by the abrasion of material through the influence of a concentrated stream of highly pressurized water entrained with abrasive particulates, have been known and used for many years. Typically, highly purified water is pressurized to upwards of 50,000 psi and is released through an abrasive waterjet cutting nozzle. As the water passes through the constricting nozzle body, it generates a vacuum via the venturi process. This vacuum serves to assist the delivery of abrasives to the water stream. Because of the venturi action, abrasive particulate material is drawn from a storage chamber and into the nozzle, is entrained in the water flow, and exits the nozzle with the water flowing at a velocity several times the speed of sound. This great speed provides the energy required to abrade the target material. However, this great speed also poses the problem of excessive consumption of the abrasive particulate. To alleviate this over consumption, a vacuum break system is typically provided.
Control of the waterjet cutting system may be by manual operation. However, it is also known, and is generally preferable, to use Computer Numeric Control (CNC) systems where the precise timing of the flow of water and inclusion of abrasive material is orchestrated with the movements of the nozzle or material being cut through the use of a computer. Such movement of the nozzle or material being cut will, therefore, be power assisted and at least partially automated.
Existing waterjet cutting machines have utilized various types of abrasive particulate materials. For example, garnet, silica, aluminum oxide, and the like, have been used as abrasive particulate materials that are mixed with water and transmitted under high pressures through an associated nozzle of waterjet cutting devices.
The operation of an abrasive waterjet cutting system requires the cutting stream to be periodically cycled from a full flow to a no flow condition, as required by the desired geometrical configuration of the part being processed. It is this starting and stopping of the cutting stream that demands an accurate and dependable delivery system because it is desirable for the flow of abrasives to be accurately timed to begin and end in coordination with the flow of water. However, several factors must be taken into consideration with regard to the timing of the waterjet cutting system.
First, to facilitate delivery of the abrasive material, it is necessary for the water flow to have begun, thus generating vacuum assist for abrasive delivery. Second, once the water flow has begun, abrasive particulate must be supplied in a controllable manner to facilitate efficient cutting of the material being processed. In the most efficient scenario, the least amount of abrasive particulate required to cut or abrade the target material is introduced to the water stream, thus minimizing any waste of the abrasive particulate. Third, the flow of abrasive particulate must be completely stopped when cutting or abrading is finished. However, water flow must not be stopped until after the last of the abrasive media in the supply conduit is expelled. If abrasive flow continues after the water flow has stopped, or does not cease far enough in advance of the water flow, abrasives may remain in the supply conduit and prevent venturi action from occurring at start-up of the next cycle. Lack of venturi action and, more specifically, the vacuum it creates will impair the transfer of abrasive particulate from the supply conduit to the waterjet cutting machine nozzle, and may halt the cutting process.
Notwithstanding the waterjet cutting systems of prior art, there has been a long felt need to improve upon their performance. For instance, one concern of waterjet cutting systems is to regulate the flow of abrasives so as to use the least amount of abrasive particulate required to efficiently cut the material being processed. Typical materials to be processed may require as little as xc2xd lb. to as great as 2 lbs. of abrasive particulate per minute of water flow. Precise control is required so as to limit the amount of abrasive particulate material wasted. It is also of importance that multiple abrasive waterjet cutting nozzles operating in tandem be supplied with equal amounts of abrasive particulates so as to perform uniformly and consistently.
There has also been a need to improve the reliability and durability of existing waterjet cutting devices. Particularly waterjet cutting devices in accordance with the prior art have been plagued by the internal scouring effect of the abrasive particulate as it passes through the system. This scouring impedes the waterjet cutting devices of the prior art from working efficiently, or from even working at all.
The present invention overcomes the shortcomings of the prior art by providing an efficient waterjet cutting system and method. The present invention also provides a highly reliable abrasive particulate material delivery system which is capable of providing accurate calibration and rapid interruption of material flow.
In accordance with one embodiment of the present invention, there is described a waterjet cutting system comprising a storage assembly in which abrasive particulate material is retained. The storage assembly includes an inlet for allowing the abrasive particulate material to flow therein, an outlet for allowing the abrasive particulate material to flow therefrom, and an inflatable diaphragm arranged at the outlet such that the inflatable diaphragm may be selectively inflated and deflated to control the flow of abrasive particulate material through the outlet. In this embodiment, the waterjet cutting system further includes a liquid supply source in communication with the storage assembly whereby the abrasive particulate material is mixed with a predetermined amount of liquid.
In accordance with another embodiment of the present invention, the waterjet cutting system further comprises a computer numeric control (CNC) system and a pressurized air supply source operatively connected to the inflatable diaphragm for selectively inflating and deflating said inflatable diaphragm.
In accordance with another embodiment of the present invention, the waterjet cutting system further comprises an air regulator device operatively connected to the pressurized air supply source for regulating the pressure of air supplied to inflate the inflatable diaphragm.
In accordance with another embodiment of the present invention, the waterjet cutting system further comprises a nozzle connected to the liquid supply source such that the abrasive particulate material and liquid may be dispersed from the nozzle at a predetermined pressure.
In accordance with another embodiment of the present invention, the storage assembly of the waterjet cutting system further comprises an upper housing retaining at least a portion of the outlet, and a lower housing connected to the upper housing. In this embodiment, the upper and lower housing have a passageway therein for permitting abrasive particulate material to flow therethrough.
In accordance with another embodiment of the present invention, waterjet cutting system storage assembly further comprises an over-inflation guard block connected to the upper housing and arranged at the outlet to prevent over expansion of the inflatable diaphragm.
In accordance with another embodiment of the present invention, the waterjet cutting system further comprises a regulation device arranged between the upper and lower housing where the regulation device regulates the amount of abrasive particulate material permitted to flow through the outlet.
In accordance with another embodiment of the present invention, the regulation device comprises a regulator orifice and a pivot pin. In this embodiment, the regulator orifice is rotatable about the pivot pin between predetermined limits to define full flow and no flow conditions.
In accordance with another embodiment of the present invention, there is provided an abrasive material delivery assembly for use with a waterjet cutting system. The abrasive material delivery assembly comprises a storage assembly in which abrasive particulate material is retained. The storage assembly includes an inlet for allowing the abrasive particulate material to flow therein, an outlet for allowing the abrasive particulate material to flow therefrom, and an inflatable diaphragm arranged at the outlet such that the inflatable diaphragm may be selectively inflated and deflated to control the flow of abrasive particulate material through through outlet.
In accordance with another embodiment of the present invention, the abrasive material delivery assembly further comprises a pressurized air supply source operatively connected to the inflatable diaphragm for selectively inflating and deflating the inflatable diaphragm.
In accordance with another embodiment of the present invention, the CNC system of the abrasive material delivery assembly further comprises an air regulator device operatively connected to the pressurized air supply source for regulating the pressure of air supplied to inflate the inflatable diaphragm.
In accordance with another embodiment of the present invention, the storage assembly of the abrasive material delivery assembly further comprises an upper housing retaining at least a portion of the outlet, and a lower housing connected to the upper housing. The upper and lower housings have a passageway therein for permitting abrasive particulate material to flow therethrough.
In accordance with another embodiment of the present invention, the storage assembly of the abrasive material delivery assembly further comprises an over-inflation guard block connected to the upper housing and arranged at the outlet to prevent over expansion of the inflatable diaphragm.
In accordance with another embodiment of the present invention, the abrasive material delivery assembly further comprises a regulation device arranged between the upper and lower housings and operable to regulate the amount of abrasive particulate material permitted to flow through the outlet.
In accordance with another embodiment of the present invention, the regulation device of the abrasive material delivery assembly comprises a regulator orifice and a pivot pin. The regulator orifice is rotatable about the pivot pin between predetermined limits to define full flow and no flow conditions.
In accordance with another embodiment of the present invention, the storage assembly of the abrasive material delivery assembly further compromises a vacuum break system. The vacuum break system comprises an air feed tube with a first end and a second end. The first end is attached to the outlet and the second end is positioned within the storage assembly at a level above that of the abrasive particulate material. The vacuum break system further comprises a filter element in communication with the interior and exterior of the storage assembly for allowing atmospheric air to enter the storage assembly. The vacuum break system is operable to selectively reduce vacuum pressure at the outlet.
In accordance with further aspects of the invention, the invention provides a method of controlling the flow of abrasive particulate material in a waterjet cutting system comprising the steps of retaining abrasive particulate material in a storage vessel; selectively inflating a diaphragm arranged at an outlet of a storage vessel to preclude the abrasive particulate material from flowing therethrough; selectively deflating the diaphragm to permit the abrasive particulate material to flow through the outlet; mixing the abrasive particulate material with a liquid so that a desired ratio of abrasive particulate material to liquid is created; and, permitting the abrasive particulate material to flow with the liquid through a nozzle of the waterjet cutting apparatus; thus creating an abrasive stream sufficient to abrade a target object.
The method of the present invention may further comprise the step of selectively inflating the diaphragm through the use of an air supply regulator assembly.
The method of the present invention may further comprise the step of utilizing a CNC system to control the air supply regulator assembly.
The method of the present invention may further comprise the step creating a vacuum environment with the storage vessel to facilitate the flow of the abrasive material through the outlet.
The above description, as well as further objects, features and advantages of the present invention will be more fully understood with reference to the following detailed description of the waterjet cutting device and method of operating such device.